Clinical organ transplantation has exploded in recent years. According to the registries of the U.S. Department of Health and Human Services and the European Dialysis and Transplantation Association, 7,000 renal transplants were performed in the U.S. and 17,000 were performed worldwide in 1984. The statistics for 1986 are estimated to show that 22,000 kidney transplants were performed throughout the world. In 1986 it is estimated that 900 liver transplants were performed worldwide.
It is now estimated that the number of kidney transplants is increasing by 15 to 20 percent annually worldwide, while liver, heart, heart/lung, bone marrow, and pancreas are increasing by approximately 30-60% annually as more organ transplant centers open up worldwide.
The introduction of the fungal cyclic peptide metabolite Cyclosporine (CsA) has been one of the most important therapeuticdevelopments in the managements of patients receiving organ allografts. While allowing for a great deal of success, immunosuppressive drugs have numerous side effects, in some cases so severe that they lead to the patient's death. The clinical challenge in organ transplantation lies in balancing the immunosuppressive effects on these drugs against their side effects. If too little immunosuppression is given, rejection of the allograft may occur, whereas too much may lead to life threatening infections and an increased incidence of malignancy as the body's normal defenses against malignancy are suppressed. Organ transplantation could be performed with much greater frequency if there were available better methods to monitor and control the body's exquisitely sensitive system of recognizing and rejecting foreign tissues.
Allograft rejection may be defined as the immunologic response to foreign tissues, which leads to loss of function of the graft and to its eventual destruction by immunocompetent cells. Rejection is easy to define but can be very difficult to diagnose in clinical practice. The principle diagnostic procedures presently available monitor organ function. These tests provide indication of decreased function of the transplanted organ, but not of rejection directly. An organ biopsy can determine more precisely whether organ disfunction is due to the onset of graft rejection or other factors such as immunosuppressive drug toxicity or infection. Typically, a physician will only decide to perform a biopsy once abnormal organ function tests have been detected.